A Novel Role for p115RhoGEF in Regulation of Epithelial Plasticity

Swapnil S Kher,Amanda P Struckhoff,Arthur S Alberts,Rebecca A Worthylake,Mirjam M Zegers

doi:10.1371/journal.pone.0085409

Abstract

Epithelial plasticity plays a critical role during physiological processes, such as wound healing and tissue regeneration, and dysregulation of epithelial plasticity can lead to pathological conditions, such as cancer. Cell-cell junctions are a critical feature of epithelial cells and loss of junctions is associated with acquisition of mesenchymal features, such as enhanced protrusion and migration. Although Rho has been implicated in regulation of junctions in epithelial cells, the role of Rho signaling in the regulation of epithelial plasticity has not been understood. We show that members of the RGS RhoGEFs family play a critical role in regulation of epithelial cell-cell junctions in breast epithelial cells. We identify a novel role for p115RhoGEF in regulation of epithelial plasticity. Loss of p115RhoGEF leads to decreased junctional E-cadherin and enhanced protrusiveness and migration. Conversely, overexpression of p115RhoGEF enhanced junctional E-cadherin and inhibited cell protrusion and migration. siRNA screen of 23 Rho effectors showed that members of the Diaphanous-Related Formin (DRF) family are required for p115RhoGEF-mediated changes in epithelial plasticity. Thus, our data indicates a novel role for p115RhoGEF in regulation of epithelial plasticity, which is dependent on Rho-DRF signaling module.

Highlights

Epithelial cells line the tissues of many organs and are highly differentiated to execute specific functions required by the breast, colon and lung
Immunofluorescent detection of E-cadherin localization showed that knockdown of p115RhoGEF disrupted localization of Ecadherin at adherens junctions, whereas PRG knockdown showed enhanced junctions as has been recently published [15]
We found that even though knockdown of either p115RhoGEF or PRG had a dramatic effect on junctional morphology, immunoblot for Ecadherin in each of the three RGS GEF knockdowns showed no change in E-cadherin expression suggesting a redistribution of Ecadherin upon loss of p115RhoGEF and PRG (Figure 1C)

Summary

Introduction

Epithelial cells line the tissues of many organs and are highly differentiated to execute specific functions required by the breast, colon and lung. Cell-cell contacts defined by tight junctions, adherens junctions and desmosomes result in apical-basolateral polarity that is essential for proper epithelial cell function. These cells help maintain tissue homeostasis and are generally nonmotile. Epithelial cells can transiently lose their cell-cell junctions and other epithelial cell characteristics to become more mesenchymal with an elongated morphology and protrusive lamellipodia that support motility. This occurs in normal physiological processes such as tubulogenesis and branching in the mammary gland, or tissue reorganization during wound healing. This inherent plasticity in the display of an epithelial phenotype enables pathophysiological consequences during diseases such as organ fibrosis or tumor metastasis [1]

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